A Micro-Electro Mechanical System (MEMS) is an integrated device capable of obtaining information, processing information, and performing operations. Sensors embedded in an MEMS system are able to sense outside information such as pressure, position, speed, acceleration, magnetic field, temperature, and humidity, and to convert the sensed information to electrical signals. The electrical signals can then be processed in the MEMS. A pressure sensor is a device capable of converting pressure signals to electrical signals.
A capacitive pressure sensor is one of the conventional pressure sensors. A conventional capacitive pressure sensor includes: a substrate; a first electrode layer on the substrate; and a second electrode layer on top of the substrate and the first electrode layer. A cavity is formed between the first electrode layer and the second electrode layer and isolates the first electrode layer from the second electrode layer.
The first electrode layer, the second electrode layer, and the cavity form a capacitive structure. When the second electrode layer is subjected to pressure and undergoes a deformation, the distance between the first electrode layer and the second electrode layer changes. The capacitance of the capacitive structure then changes accordingly. Since the pressure on the second electrode layer corresponds to the capacitance of the capacitive structure, the pressure on the second electrode layer can be converted to an output signal of the structure.
However, the conventional pressure sensor lacks electrical stability.